But no defeat devices were detected by government authorities.

France finds nine car companies break pollution rules

Some cars on French roads do not meet carbon dioxide limits, but the French government said on Thursday it had not found any equipped with software to cheat pollution tests.

French Ecology minister Segolene Royal ordered tests on a random sample of about 100 diesel cars last year after Germany's Volkswagen admitted that 11 million of its diesel vehicles had "defeat devices" which allowed them to meet emissions rules in test conditions.